Control device for radio receivers and the like



1942' L. H. ZEPP 2,285,247

QONTROL DEVICE FOR RADIO RECEIVERS AND THE LIKE Filed March 10, 1938 4Sheets-Sheet l I zwewaz "2'- Z9700 ,5 Mug/252274595 ne 1 L. H. ZEPP2,285,247

CONTROL DEVICE FOR RADIO RECEIVERS AND THE LIKE Filed March 10, 1938 4Sheets-Sheet 2 lune 1942. L. H. ZEPP4 2,285,247

CONTROL DEVICE FOR RADIO RECEIVERS AND THE LIKE Filed March 10, 1958 4Sheets-Sheet 3 June 2, L. HQZEPP 2,285,247

I CONTROL DEVICE FO R RADIO RECEIVERS AND THE LIKE Filed March 10, 19384 Shegts-Sheet 4 VIIIII/I/ Patented June 2, 1942 CONTROL DEVICE FORRADIO RECEIVERS AND THE LIKE Louis B. Zepp, Philadelphia, Pa., assignor,by

mesne assignments, to Philco Radio and Television Corporation,Philadelphia, Pa., a'corporation of Delaware Application March 10, 1938,Serial No. 195,182

9 Claims. (CI. 74-10) This invention relates to new and usefulimprovements in tuning control devices for radio receivers and moreparticularly tuning control devices of the push button operated type.

The principal object of the present invention is to provide a device ofthe character set forth having novel mechanism for positively andaccurately turning the condenser or other tuning element of a radioreceiving set into a predetermined position corresponding to the wavelength of a selectedradio station.

Another equally important object of the invention is to provide a-radiotuning device of the push-button-operated cam-controlled type which isoperable to effect relatively easy, rapid tuning of the receiver and isconstructed and arranged to positively control actuation of the camsen'- tirely to their final rest or tuning positions thus eliminatingover carry thereof and insuring precision tuning of the radio receiver.

A still further object of the invention is to provide apush-button-actuated cam-controlled radio tuning device of the characterset forth which embodies novel features of construction and arrangementwhereby the several cams, or any of them, may be quickly and easilyadjusted into any predetermined tuning position desired.

A still further object of the invention is to provide a radio receivingset tuning device of the type described which is comparativelyinexpensive to manufacture and, as respects its external operatinginstrumentalities, does not destroy or detract from the general externalappearance of the cabinet in which it and the radio receiver aremounted.

These and other objects of the invention and the features and details ofits construction and operation are hereinafter fully set forth and shownin the accompanying drawings, in which:

Figure 1 is a front elevation view of a tuning device embodying theinvention in association with a radio receiving set of the cabinet type;

certain details of construction of a forming a feature of the invention;

Figure is a view in perspective of a plate or member constituting a part.of the frame gear wheel structure for the mechanism] and arranged forcooperative association with the gear wheel shown in Figure 9 andFigures 2 and 3 are end elevation and plan viewsrespectively of thedisclosure in Figure 1; Figure 4 is an enlarged fragmentary view insection taken on line A-A Figure 1;

Figure 5 is a plan view of one of several washers embodied in theinvention;

Figures 6, 7 and 8 are fragmentary views partially in section on line3-3 Figure 3 showing the relationship of various elements of the mech--anism when the cams are in inoperative, intermediate and operative orfinal rest positions;

Figure 9 is a view in perspective illustrating Figure 11 is a detachedfragmentary view illustratingthe angular arrangement or mounting of theplunger springs.

Referring now more particularly to Figure 1 of the drawings, the tuningmechanism is shown as mounted within the cabinet I of a radio receivingset which has as its tuning element a variable condenser 2 supportedendwise of said tuning mechanism by a bracket or plate 3 to which it.

is connected by means of resilient bushings 4 so that its shaft 5extends horizontally and longitudinally of the cabinet.

The tuning mechanism comprises a frame structure including end or sideplate members 8 and l in which a shaft 8 is joumalled. The journal forthe shaft 8 in the plate I is provided by the projecting hub portion 9of a gear wheel III which has a key or projection H thereon arranged toengage a groove l2 extending lengthwise of the shaft 8 thus slidablykeying said gear l0 thereon. The gear is fixedly positioned relative tothe plate I at the condenser side thereof by virtue of a C'type washerl3 which is mounted in a slot or groove ll in the hub portion 9 thereofand engages the opposite face of the plate 1 as shown in Figure 4 of thedrawings.

For a purpose that will later appear, rotation of the shaft 8 is limitedto approximately degrees by means of a lug or projection IS on the faceof the gear lfl which is arranged to move within the longer distancebetween stops l6 and I! pressed out from the frame plate I. As shown,the shaft 8 is operatively connected to the shaft 5 of the condenser 2through the gear l0, a gear I8 and its shaft l9 which is journalled in aportion or arm 20 of the frame structure. One end of this shaft I9 isconnected to the condenser shaft 5 by means of a resilient couplingmember 2| and in order to effect the requisite approxi mately degreesrotationof the condenser 2 and its shaft 5, the ratio of the diametersof the gears l0 and I8 is such that rotation of the shaft 8 and gear inthrough 145 degrees will cause said condenser and its shaft to rotatethrough approximately 180 degrees.

Also keyed upon the shaft 8 at the condenser side of the plate 1 is asecond gear 22 which is spaced from the gear 10 by means of a sleeve 23.

A pointer 24 of any usual or suitable construction is carried by a shaft25 and exposed in cooperative association with a dial in theconventional manner through an opening to the front face of the cabinetI to indicate the setting of the device. This shaft 25 has fixed thereona pulley 26 and a gear 21 which meshes with the said gear 22 thusoperatively connecting the said shaft 25 and pointer 24 to the condenser2 through the shaft 8, gears l6 and I8 and shaft l8. A belt or cable28passes about the .pulley 26 and also a smaller pulley 29 carried by ashaft 38 which projects beyond the front face of the cabinet I and isprovided with a suitable button or knob (not shown) by means of whichsaid shaft 36 may be rotated to drive the pulley 26 through said cable28 and hence turn the pointer 24, shaft 8 and the condenser 2 throughthe aforementioned gear connections to manually tune the receiver inaccompaniment to movement of said pointer 24 relative to the dial toindicate the setting of said condenser in the usual manner.

Mounted upon the shaft 8 at the opposite side of the frame plate 1 are aplurality of cam elements 3| which under certain conditions are intendedto be adjusted relative to the shaft 8 and therefore are not keyedthereon. The cams 3| are spaced relative to one another by means ofsleeves 32 and washers 33, the latter being disposed at opposite sidesof each such cam between it and the adjacent sleeve. These washers 33are of the general construction shown in Figure and include 9. lug orprojection 34 for engagement with the groove |2 in shaft 8 so that saidwashers 33 rotate therewith.

As shown in Figure 4, the innermost sleeve 32 is connected to theadjacent or inner end of the shaft 8 by means of a pin 35. On the otherhand, the opposite or outer end of the shaft 8 is threaded and'engages athreaded socket portion 36 provided in a locking and adjusting member 31which is journalled in the cabinet I and has a cup shaped inner endportion 38 which, when the member is tightened upon the shaft, normallyabuts or engages the outer face of the hub portion of the gear 22. Theother or outer end of the member 38 is provided with an enlarged head 33which resides within a recess 46 flush with the external surface of theend of said cabinet and has a slot or groove 4| therein to enableturning of said member 31 by means of a screw driver, cam or the like.The inner cup shaped portion 38 of the member 31 provides sufficientclearance for a coil spring 42 which surrounds the shaft 6 and actsbetween the adjacent hub face of the gear 22 and a C type washer 43which engages a groove 44 in said shaft and acts as a stop or abutmentfor said spring 42.

From the foregoing description it will be seen that when the lockingmember 31 is tightened upon the shaft and resides firmly against theface of the hub of the gear 22 pressure is exerted through the sleeves32 and washers 33 upon the cams 3| with the result that the latter aresecurely bound and gripped therebetween to an extent affording in effecta unitary structure or assembly rotatable with the shaft 8. On the otherhand, when the locking member 31 is loosened sufficiently the grip uponthe cams 3| afforded by the sleeves 32 and washers 33 is lessened to anextent permitting adjustment of said cams circumferentially of the shaft8 as desired although when said member 31 is thus loosened the spring 42exerts suflicient pressure upon the aaaaau cams 3| through the sleeves32 and washers 33 to normally hold said cams in position upon said shaftduring adjustment of any one cam thereon until said locking member isagain tightened against the gear 22.

Assuming for the present that the cams 3| are in desired positions ofadjustment circumferentially of the shaft 8, actuation of said cams 3|and consequently the shaft 8, condenser 2 and pointer 24 is effected bymeans of plungers 46 which are mounted for movement within predeterminedlimits vertically within the cabinet I, and provided with buttonelements 41 at their upper ends which project a suitable distance abovethe top of the cabinet l as indicated in Figure 1. The plungers 46 areeach provided with a slot 48 therein through which the shaft 8 and oneof the spacing sleeves 32 extends and the length of said slots 48 issuch as to determine the limits and extent of movement of the plungera46 inwardly of the cabinet I with respect to the said shaft 3 and cams3| thereon, said plungers 46 being normally urged outwardly of thecabinet I by means of springs 48 which are connected at an angle betweensaid plungers and the v portion 50 of the frame structure of the tuningmechanism as shown in Figure 11 for the purpose of preventing rattling.

As shown particularly in Figures 6, '1 and 8 of the drawings, engagementand rotation of the cams 3| and consequently the shaft 8 is accomplishedby means of a pair of rollers 5| and 52 carried by each plunger 46 inhorizontally spaced relation at respectively opposite sides of the axisof movement of said plungers. The distance between the centers of therollers 5| and 52 and the length of stroke of the plungers 46 as limitedby the slots 48 is preferably of the ratio of approximately one to one,said ratio affording maximum over all precision through a large angle ofrotation.

Precision, as herein used, relates to the measure of the possibleangular rotation of the shaft 8, and hence the condenser 2, when theplunger 46 is not fully depressed but is a small fixed distance whichmight be called a tolerance from the lowermost position of the plungerstroke and obtains from the fact the distance from the center ofrotation of the cams 3| to the point of contact thereof with the rollers5| and 52 increases as the distance between said rollers is increased,and also the fact that with a given tolerance the angle through whichthe cam. is

free to rotate varies inversely with the last mentioned distance.

Due consideration must be given to the form or contour of the cams 3|and for purposes of description, the several portions of said cams areherein designated as the nose n, shoulders s and heel h and theseportions will be individually considered inasmuch as. the requirementsfor each such portion are different. The nose portions n of the cams 3|preferably have a curvature such that the angular velocity of said camsis proportional to the linear velocity of the plungers 46 and as thiscurvature may be determined by any one of several well known methodsfurther comment in that regard is deemed unnecessary. However,considerable care and study must be given the selection of the properradius of curvature of the shoulder portions s of the cams 3| since thisportion determines the behavior of said cams during a critical period ofrotation thereof.

It will be seen upon reference to Figures 6, 7

and 8 of the drawings that the maximum distance between the shoulderportions 3 of each of the'cams 3| is necessarily greater than thedistance between the innermost points on the peripheries of the rollers5| and 52 carried by l the plungers l5, and in the present design theformer distance is less than the distance between the centers ofrotation of said rollers. Further, the circular heel portions h of thecams 3| have a diameter that is equal to the distance between theperipheries of the plunger rollers 5| and 52.

The principal objective in the design of the contour of the cams 3| andparticularly the shoulder portions 3 thereof is to obtain a markeddecrease in the angular velocity of said cams as they approach the restposition and also to eliminate any possibility of rebound when the camsreach such'rest position. In the present instance, these objectives areobtained by designing the cams 3| so that the periphery of the shoulderportions s thereof approaches but does not become tangent to any radialline r drawn through the center .of rotation of said cams 3| as shown inFigure 7, and by further designing the cams so that the periphery ofsaid shoulder portions 8 is interceptedby any such radial line 1 at buta single point therealong.

It will be observed particularly with reference I to Figures 7 and 8 ofthe drawings that the radius of curvature of the shoulder and heelportions s and h respectively of the cams is such that the periphery ofsaid cams in the region of the point of contact approaches a relationparallel to the direction of movement of the plungers with the resultthat with a given tolerance the angular play of the cams is minimized,

and thatpartof each of the rollers 5| and 52- which is in contact withthe cam is permitted to pass a short distance below the center ofrotation of said cams thus affording maximum precisionin the ultimatepositioning of the cams at all times since any wear, play or loosenessbetween the shaft 8 and its bearings or the cams 3| and rollers 5|and.;52 is compensated for by the opposing forces provided by contact ofthe rollers 5| and 52 with opposite sides of said cams and thus forciblyopposing possible carryover of the cams beyond their final restpositions.

To set each cam 3| in proper position upon the shaft 8 so as to bringthe receiving circuit into resonance'with the particular stationrepresented by its associated plunger 46, the locking member 31 isloosened with respect to said shaft 8 as above described to releasecompression upon the cams 3| to an extent sufficient to permit them tobe rotated upon the shaft 8 by the application of positive force againstthe compression afforded by the spring I! which continues to exertsuiiicient pressure upon said cams to otherwise hold them in position.The stop H on the frame plate I is provided primarily to afford a strongrigid abutment to limit rotation of the shaft 8 in one direction andagainst which the looking member 31 may be loosened with respect to saidshaft 8 without danger of possible damage to the movable plates of thecondenser 2 which might otherwise occur were rotation of the shaft 8limited solely by the extent of rotation of the movable plates of thecondenser. After the looking member 31 has been loosened as described,the receiving set is turned on and the plunger 45 selected to representa desired station is depressed to engage and actuate its associated cam3| into operative rest position after which the receiving set ismanually tuned to that station to position said cams 3| and shaft 8 inthe propercircumferential relation with respect to each other so thatthe receiving circuit may be brought into resonance with said selectedstation at each subsequent depression of the plunger or at least untilsaid cam 3| may be adjusted to a different position upon said shaft.

The other cams 3| may then be similarly adjusted upon the shaft8according to the particular station to be represented by theirassociated plungers 48 and until all of the cams are thus set thecompression afforded by the spring 4| is sufficient to maintain each camin the position to which it may be adjusted circumferentially of theshaft 8. When any or all of the cams 3| have been adjustedcircumferentially of the shaft 8 as aforementioned, the locking member38 is tightened upon. the shaft 8 which is moved to its other limit ofrotation provided by the stop I8 on the frame plate I which affords astrong rigid abutment against which the lockthe tuning condenser 2.

respect to the shaft 8 without danger of pos sible damage to the movableplate assembly of In the same manner, the cams 3|, or any of them, maybe reset from time to time as desired.

From Figures 6, '7 and 8 of the drawings it will be observed that theconstruction and arrangement of the cams 3|and rollers 5| and 52 car'-ried by each associated plunger is such that in the final rest or tuningposition of each cam the long axis thereof lies in the direction ofmovement of its plunger which in the present instance is vertical withrespect to the radio receiverand its cabinet I.

Generally the plungers 46 will be permitted to return immediately totheir inoperative outward positions under the influence of the springs II 3 43 as soon as the cams 3| have been actuated thereby into final restor tuning positions. However, in certain installations such as inautomobiles, small boats, airplanes and the like where vibration may besufficient to jar the cams 3| from final rest or tuning position in theevent that they are not held in such position by the rollers 5| and 52carried by the plungers, a suitable lock or latch mechanism may beprovided whereby the plungers 46 are held in inward cam positioningrelation at least during such period that it is desired they remain insuch tuning position.

In the present instance such locking mechanism for the plungers 48comprises a latch member 53 which is common to all of said plungers andpivotally mounted in the frame structure of the device as indicated at54. A leaf spring 55 constantly urges the latch member 53 in acounterclockwise direction ,with respect to Figures 6 and 8 of thedrawings into the path of the plungers 45 with the result that as thelatter reach the limit of inward movement and the cams 3| reach finalrest or tuning position said leaf spring 55 causes the latch member 53to engage a notch 56 in each plunger 45.

By providing a common latch member accordto return it to inoperativeposition. Such other plunger may then be released or moved fully inwardto engage the latch 53 with its notch 56 so as to lock said otherplunger and its cam in tuning position where it will be held by saidlatch 53 until still another plunger is depressed a sumcient distance toengage and release the latch from the notch 56 of the plunger thus held.

While a particular embodiment of the invention has been hereinillustrated and described, it is not intended that the invention beprecisely limited to that form of device, but that changes andmodifications in construction and arrangement may be embodied orincorporated therein within the scope of the annexed claims.

I claim:

1. In a device of the character described, a shaft, a cam mounted onsaid shaft for rotation therewith, said cam having a curved periphery, amanually operable member having a stroke of predetermined fixed lengthassociated with said cam, a pair of actuating elements carried by saidmember and arranged to engage the associated cam at opposite sides ofthe axis of rotation of the cam to rotate the same and said shaft into apredetermined position, the curvature of the cam bearing such relationto the stroke of said member and the location and distance between theactuating elements carried thereby that as said cam approaches finalrest position, said actuating elements contact the cam at opposite sidesthereof and below its center of rotation to insure positive accuratepositioning thereof in said final rest position.

2. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device for tuning said elementcomprising a cam shaft operatively connected to the shaft of the tuningelement, a plurality of cam elements mounted on said shaft for rotationtherewith, said cam elements each having a curved periphery, a manuallyactuable member associated with each of said cams, and a pair ofactuating elements carried by each member and arranged to engage theassociated cam at opposite sides of theaxis of rotation of said cam torotate the same, said cam shaft and tuning element into a predeterminedposition, the curvature of said cams bearing such relation to the strokeof the members and the location and distance between the actuatingelements carried thereby that as the cams approach final tuningposition, said actuating elements contact said cams at opposite sidesthereof and below the center of rotation of the cams to insure positiveaccurate positioning thereof into tuning position.

3. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device for tuning said elementcomprising a cam shaft operatively connected to the shaft of the tuningelement, a plurality of cam elements mounted on said shaft for rotationtherewith, said cam elements each having a curved periphery, a manuallyactuable member for each of said cams, a pair of actuattuating elementscontact said cams at opposite sides thereof and below the center ofrotation of the cams to insure positive accurate positioning thereofinto tuning position, and means associated with each member tending tourge the same into inoperative relation with respect to said cams.

4. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device for tuning said elementcomprising a cam shaft operatively connected to the shaft of the tuningelement, means for positively restrictin rotation of the cam shaftbetween predetermined limits, a plurality of cam elements mounted onsaid shaft for rotation therewith, said cam elements each having acurved periphery, a manually actuable member for each of said camshaving a stroke of predetermined fixed length, and a pair of actuatingelements carried by each member and arranged to engage the associatedcam at opposite sides of the axis of rotation of said cam to rotate thesame, said cam shaft and tuning element into a predetermined position,the curvature of the cams bearing such relation to the stroke of themembers and the location and distance between the actuating elementscarried thereby that as the cams approach final tuning position, saidactuating elements contact said cams at opposite sides thereof at pointsbelow the center of rotation of the cams to insure positive accuratepositioning thereof into tuning position.

5. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device for tuning said elementcomprising a cam shaft operatively connected to the shaft of the tuningelement, a plurality of cam elements mounted on said shaft forindependent angular adjustment thereon, said cam elements each having acurved periphery, means for securing said cams for rotation with saidcam shaft in any adjusted position and for freeing said cams withrespect to said shaft to permit adjustment of the cams thereon, amanually actuable plunger for each of said cams, a pair of rolls carriedby each plunger and arranged to engage the associated cam at oppositesides of the axis of rotation of said cam to rotate the same, said camshaft and tuning element into a predetermined position, the curvature ofsaid cams bearing such relation to the stroke of the plungers and thelocation and distance between the rolls carried thereby that as the camsapproach final tuning position, said rollers engage the cams at oppositesides thereof at points below the center of rotation of the cams toinsure positive accurate positioning thereof into tuning position, and aspring actuated latch member arranged to engage a notch in each plungeras it reaches the limit of its operative stroke to hold said plunger inthat position.

6. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device for tuning said elementcomprising a cam shaft operatively connected to the shaft of the tuningelement, means for positively restricting rotation of the cam shaftbetween predetermined limits, a plurality of cam elements mounted onsaid shaft for independent angular adjustment thereon, said cam elementseach having a curved periphery, means for securing said cams forrotation with said cam shaft in any adjusted position and for freeingsaid cams with respect to said shaft to permit adjustment of the camsthereon, a manually actuable plunger for each of said cams having astroke of predetermined fixed length, a pair of rolls carried by eachplunger and arranged to engage the associated cam at opposite sides ofthe axis of rotation of said cam to rotate the same, said cam shaft andtuning element into a predetermined position, the curvature of said camsbearing such relation to the stroke of the plungers and the location anddistance between the rolls carried thereby that as the cams approachfinal tuning position, said rollers engage the cams at opposite sidesthereof at points below the center of rotation of the cams to insurepositive accurateZ positioning thereof into tuning position, and aspring actuated latch member arranged to engage a notch in each plungeras it reaches the limit of its operative stroke to hold said plunger inthat position,

7. In a radio receiving set having as its tuning element at least onerotatable member provided with a shaft, a device comprising a cam shaftoperatively connected to the shaft of the tuning element, a plungerconstructed and arranged to move along a path passing through the axisof said cam shaft, a pair of spaced rollers carried by said plunger, anda cam on the cam shaft arranged for rotation by depressing the plunger,said cam having a nose portion arranged for contact by only one of saidrollers to rotate the cam substantially uniformly as said plunger isdepressed, a shoulder portion having a rapidly decreasing butsingle-valued radius to 'reduce the rate of rotation of said cam, and aheel portion arranged to seat a substantial portion of each of therollers when the plunger is in its final rest position, the portion ofsaid rollers in contact with said heel portion of the cam being belowthe axis of rotation of the cam shaft.

8. In a device of the character described, a

shaft, a cam having a curved periphery mounted on said shaft forrotation therewith, a manually operable member, a pair of actuatingelements carried by said member and arranged to engage the cam atopposite sides of its axis'of rotation to rotate the same and said shaftinto a predetermined position, said cam comprising spaced shoulderportions having a single valued radius which rapidly decreases from amaximum distance between said shoulder portions greater than the spacebetween said actuating elements, and a heel portion having a radiussubstantially equal to the space between the actuating elementscooperatively associated with said shoulder portions whereby a markeddecrease in the angular velocity of said cam as it approaches restposition is effected.

9. In a device of the character described, a shaft, a cam having acurved periphery mounted on said shaft for rotation therewith, amanually operable member, a pair of actuating elements carried by saidmember and arranged to engage the cam at opposite sides of its axis ofrotation to rotate the same and said shaft into a predeterminedposition, said cam comprising spaced shoulder portions having a singledvalued radius which rapidly decreases from a maximum distance betweensaid shoulder portions greater than the space between said actuatingelements, and a heel portion having a radius substantially equal to thespace between the actuating elements cooperatively associated with saidshoulder portions and merging therewith in a sector which isapproximately tangent to a line drawn through the center of rotation ofthe cam whereby a marked decrease in the angular velocity of said cam asit approaches rest position is efiected.

LOUIS H. ZEPP.

